Viktor is a great example of how power creep has single handedly ruined a champion
Remember why Viktor used to be such a strong pick? Strong damage and spikes with every item, and his absurd waveclear. Also lets not forget his amazing levels 1 and 2 trading.
Now look at this complete fucking mess of a champion.
Forced to buy a 1250 item on first back, only viable build is tank (abyssal + iceborn), only viable keystone is a clearly overloaded adc rune not even designed for him, and he can't even one shot waves anymore once he gets his hextech upgrade.
Now look at other champions.
Let's start with Malzahar. He can buy lost chapter, a 900 gold item that gives better stats than viktor's hexcore upgrade, and actually fixes his mana problems with a strong statline and passive, unlike viktor's added flat mana on his hexcore upgrade. He has a keystone that synergizes well with his kit, and has good scaling. He's a threat even when behind due to his ult. Meanwhile Viktor behind is basically just a squishy ranged w bot who kites around while dealing fuck all in terms of damage. To top all this off, Malzahar doesn't even need to worry about trades BECAUSE HE CAN ONE SHOT THE CASTER WAVE LEVEL 1. YES. Viktor's ONLY redeeming quality is now not even considered on par with other midlaners.
Zoe as well. She has the same itemization as Malzahar, and can one shot enemies behind or ahead. She also has comperable, if not better waveclear than Viktor. I don't play much Zoe, but I'm fairly certain she can one shot the casters much faster than viktor.
Qualities that once made Viktor a great midlaner are now overshadowed by the fact that every midlaner and their mother can one shot the backline in one to two abilities now adays, and much earlier as well.
And now they have to buff Viktor just to stay somewhat relevant with these ridiculous abominations of champions.